In a small bowl, mix the maple syrup, soy sauce, garlic, garlic salt, and pepper.
Place salmon in a shallow glass baking dish, and coat with the maple syrup mixture. Cover the dish, and marinate salmon in the refrigerator 30 minutes, turning once.
Grill the fish skin down, for about 2mins each side, until skin turns brown.
Preheat oven to 400 degrees F (200 degrees C).
Place the baking dish in the preheated oven, and bake salmon uncovered 20 minutes, or until easily flaked with a fork.